The present invention relates generally to the art of transparent coatings and more particularly to multiple layer colored transparent coatings, especially for use on architectural glass products.
Architectural glass products with metallic and/or metal oxide films are growing in importance as energy demands for heating and cooling become increasingly expensive. Coated glass architectural products generally fall into two categories, solar energy control and high transmittance, low emissivity coated products.
Solar energy control glass products are generally glass substrates, often tinted, coated with a low visible transmittance colored film which reduces solar energy transmittance through the windows into the building interior, thereby reducing air conditioning costs. These products are most effective in warm climates and are most often seen in commercial construction. In areas where heating costs are of greater concern, and particularly in residential construction, high transmittance, low emissivity coatings are desirble in order to allow high transmittance of visible light into the interior while reflecting infrared radiation to retain heat inside the building. High transmittance, low emissivity coatings are typically multiple layer films wherein an infrared reflecting metal such as silver, gold or copper is sandwiched between anti-reflective metal oxide layers such as bismuth, indium and/or tin oxides. Solar energy control films, on the other hand, are typically single layer films of one or more of the metals or oxides of metals such as cobalt, iron, chromium, nickel, copper, etc.
Wet chemical methods for producing metallic films for solar energy control are well known from U.S. Pat. Nos. 3,846,152; 4,091,172; 3,723,158 and 3,457,138. Pyrolytic methods for producing metal oxide films for solar energy control are well known from U.S. Pat. Nos. 3,660,061; 3,658,568; 3,978,272 and 4,100,330.
Sputtering technologies for producing high transmittance, low emissivity multiple layer coatings are disclosed in U.S. Pat. Nos. 4,462,884 and U.S. Pat. No. 4,508,789. Sputtering techniques for producing solar control films are disclosed in U.S. Pat. Nos. 4,512,863 and 4,594,137.
U.S. Pat. No. 4,022,947 to Grubb et al discloses a transparent panel capable of transmitting a desired portion of visible radiation while reflecting a large portion of incident solar radiation, and a method of preparing same, by sputtering an iron, nickel and chromium alloy to obtain a transparent metal film, and reactively sputtering the same or a similar alloy in the presence of oxygen to form an oxide film. In one preferred embodiment, the metal film lies between the substrate and the metal oxide film. In another preferred embodiment, the metal oxide film lies between the substrate and the metal film.